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From: Taylor Blau <me@ttaylorr.com>
To: Patrick Steinhardt <ps@pks.im>
Cc: git@vger.kernel.org, Chris Torek <chris.torek@gmail.com>,
	Derrick Stolee <derrickstolee@github.com>,
	Jeff King <peff@peff.net>, Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH v2 09/16] refs/packed-backend.c: implement jump lists to avoid excluded pattern(s)
Date: Tue, 20 Jun 2023 08:15:07 -0400	[thread overview]
Message-ID: <ZJGYS7D3fusfcou3@nand.local> (raw)
In-Reply-To: <ZH7ZpB8eMBZN8q63@ncase>

On Tue, Jun 06, 2023 at 09:00:52AM +0200, Patrick Steinhardt wrote:
> > @@ -785,6 +802,13 @@ struct packed_ref_iterator {
> >  	/* The end of the part of the buffer that will be iterated over: */
> >  	const char *eof;
> >
> > +	struct jump_list_entry {
> > +		const char *start;
> > +		const char *end;
> > +	} *jump;
> > +	size_t jump_nr, jump_alloc;
> > +	size_t jump_pos;
> >
> Nit: I had some trouble with `jump_pos` given that it sounds so similar
> to `iter->pos`, and thus you tend to think that they both apply to the
> position in the packed-refs file. `jump_curr` or `jump_idx` might help
> to avoid this confusion.

Very fair, thanks for observing. I went with "jump_cur" (as a shorthand
for "cursor").

> > +	for (pattern = excluded_patterns; *pattern; pattern++) {
> > +		struct jump_list_entry *e;
> > +
> > +		/*
> > +		 * We can't feed any excludes with globs in them to the
> > +		 * refs machinery.  It only understands prefix matching.
> > +		 * We likewise can't even feed the string leading up to
> > +		 * the first meta-character, as something like "foo[a]"
> > +		 * should not exclude "foobar" (but the prefix "foo"
> > +		 * would match that and mark it for exclusion).
> > +		 */
> > +		if (has_glob_special(*pattern))
> > +			continue;
> > +
> > +		ALLOC_GROW(iter->jump, iter->jump_nr + 1, iter->jump_alloc);
> > +
> > +		e = &iter->jump[iter->jump_nr++];
> > +		e->start = find_reference_location(snapshot, *pattern, 0);
> > +		e->end = find_reference_location_end(snapshot, *pattern, 0);
>
> Nit: we could detect the non-matching case here already, which would
> allow us to skip an allocation. It's probably pre-mature optimization
> though, so please feel free to ignore.

Probably so, this allocation is so lightweight in comparison to all of
the other things that for-each-ref does throughout its execution that I
think it's probably negligible to shave off a few allocations.

> > +	}
> > +
> > +	if (!iter->jump_nr) {
> > +		/*
> > +		 * Every entry in exclude_patterns has a meta-character,
> > +		 * nothing to do here.
> > +		 */
> > +		return;
> > +	}
> > +
> > +	QSORT(iter->jump, iter->jump_nr, jump_list_entry_cmp);
> > +
> > +	/*
> > +	 * As an optimization, merge adjacent entries in the jump list
> > +	 * to jump forwards as far as possible when entering a skipped
> > +	 * region.
> > +	 *
> > +	 * For example, if we have two skipped regions:
> > +	 *
> > +	 *	[[A, B], [B, C]]
> > +	 *
> > +	 * we want to combine that into a single entry jumping from A to
> > +	 * C.
> > +	 */
> > +	last_disjoint = iter->jump;
>
> Nit: if we initialized `j = 0`, then `last_disjoint` would always be
> equal to `iter->jump[j]`. We could then declare the variable inside of
> the loop to make it a bit easier to understand.

Sure, though we would then need to assign `iter->jump_nr = j + 1`, which
I think adds more confusion than inlining the variable is worth.

Thanks,
Taylor

  reply	other threads:[~2023-06-20 12:15 UTC|newest]

Thread overview: 149+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-08 21:59 [PATCH 00/15] refs: implement skip lists for packed backend Taylor Blau
2023-05-08 21:59 ` [PATCH 01/15] refs.c: rename `ref_filter` Taylor Blau
2023-05-08 21:59 ` [PATCH 02/15] ref-filter.h: provide `REF_FILTER_INIT` Taylor Blau
2023-05-08 21:59 ` [PATCH 03/15] ref-filter: clear reachable list pointers after freeing Taylor Blau
2023-05-08 21:59 ` [PATCH 04/15] ref-filter: add ref_filter_clear() Taylor Blau
2023-05-08 22:29   ` Junio C Hamano
2023-05-08 22:33     ` Taylor Blau
2023-05-09 15:14   ` Patrick Steinhardt
2023-05-09 19:11     ` Taylor Blau
2023-05-08 21:59 ` [PATCH 05/15] ref-filter.c: parameterize match functions over patterns Taylor Blau
2023-05-08 22:36   ` Junio C Hamano
2023-05-09 20:13     ` Taylor Blau
2023-05-08 21:59 ` [PATCH 06/15] builtin/for-each-ref.c: add `--exclude` option Taylor Blau
2023-05-08 23:22   ` Junio C Hamano
2023-05-09 20:22     ` Taylor Blau
2023-05-08 22:00 ` [PATCH 07/15] refs: plumb `exclude_patterns` argument throughout Taylor Blau
2023-05-09 15:14   ` Patrick Steinhardt
2023-05-09 20:23     ` Taylor Blau
2023-05-08 22:00 ` [PATCH 08/15] refs/packed-backend.c: refactor `find_reference_location()` Taylor Blau
2023-05-08 23:56   ` Junio C Hamano
2023-05-09 20:29     ` Taylor Blau
2023-05-08 22:00 ` [PATCH 09/15] refs/packed-backend.c: implement skip lists to avoid excluded pattern(s) Taylor Blau
2023-05-09  0:10   ` Chris Torek
2023-05-09 20:39     ` Taylor Blau
2023-05-09 15:15   ` Patrick Steinhardt
2023-05-09 20:55     ` Taylor Blau
2023-05-09 21:15       ` Taylor Blau
2023-05-10  7:25       ` Patrick Steinhardt
2023-05-09 23:40   ` Junio C Hamano
2023-05-10  2:30     ` Taylor Blau
2023-05-08 22:00 ` [PATCH 10/15] refs/packed-backend.c: add trace2 counters for skip list Taylor Blau
2023-05-08 22:00 ` [PATCH 11/15] revision.h: store hidden refs in a `strvec` Taylor Blau
2023-05-08 22:00 ` [PATCH 12/15] refs/packed-backend.c: ignore complicated hidden refs rules Taylor Blau
2023-05-08 22:00 ` [PATCH 13/15] refs.h: let `for_each_namespaced_ref()` take excluded patterns Taylor Blau
2023-05-08 22:00 ` [PATCH 14/15] upload-pack.c: avoid enumerating hidden refs where possible Taylor Blau
2023-05-09 15:15   ` Patrick Steinhardt
2023-05-09 21:34     ` Taylor Blau
2023-05-08 22:00 ` [PATCH 15/15] builtin/receive-pack.c: avoid enumerating hidden references Taylor Blau
2023-05-15 19:23 ` [PATCH v2 00/16] refs: implement jump lists for packed backend Taylor Blau
2023-05-15 19:23   ` [PATCH v2 01/16] refs.c: rename `ref_filter` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 02/16] ref-filter.h: provide `REF_FILTER_INIT` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 03/16] ref-filter: clear reachable list pointers after freeing Taylor Blau
2023-05-15 19:23   ` [PATCH v2 04/16] ref-filter: add `ref_filter_clear()` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 05/16] ref-filter.c: parameterize match functions over patterns Taylor Blau
2023-05-15 19:23   ` [PATCH v2 06/16] builtin/for-each-ref.c: add `--exclude` option Taylor Blau
2023-05-15 19:23   ` [PATCH v2 07/16] refs: plumb `exclude_patterns` argument throughout Taylor Blau
2023-05-15 19:23   ` [PATCH v2 08/16] refs/packed-backend.c: refactor `find_reference_location()` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 09/16] refs/packed-backend.c: implement jump lists to avoid excluded pattern(s) Taylor Blau
2023-06-06  7:00     ` Patrick Steinhardt
2023-06-20 12:15       ` Taylor Blau [this message]
2023-05-15 19:23   ` [PATCH v2 10/16] refs/packed-backend.c: add trace2 counters for jump list Taylor Blau
2023-05-15 19:23   ` [PATCH v2 11/16] revision.h: store hidden refs in a `strvec` Taylor Blau
2023-06-06  7:00     ` Patrick Steinhardt
2023-06-20 12:16       ` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 12/16] refs/packed-backend.c: ignore complicated hidden refs rules Taylor Blau
2023-05-15 19:23   ` [PATCH v2 13/16] refs.h: let `for_each_namespaced_ref()` take excluded patterns Taylor Blau
2023-06-06  7:01     ` Patrick Steinhardt
2023-06-20 12:18       ` Taylor Blau
2023-05-15 19:23   ` [PATCH v2 14/16] builtin/receive-pack.c: avoid enumerating hidden references Taylor Blau
2023-05-15 19:23   ` [PATCH v2 15/16] upload-pack.c: avoid enumerating hidden refs where possible Taylor Blau
2023-05-15 19:23   ` [PATCH v2 16/16] ls-refs.c: " Taylor Blau
2023-06-06  7:01   ` [PATCH v2 00/16] refs: implement jump lists for packed backend Patrick Steinhardt
2023-06-20 12:22     ` Taylor Blau
2023-06-07 10:40 ` [PATCH v3 " Taylor Blau
2023-06-07 10:40   ` [PATCH v3 01/16] refs.c: rename `ref_filter` Taylor Blau
2023-06-13 22:19     ` Junio C Hamano
2023-06-07 10:40   ` [PATCH v3 02/16] ref-filter.h: provide `REF_FILTER_INIT` Taylor Blau
2023-06-07 10:41   ` [PATCH v3 03/16] ref-filter: clear reachable list pointers after freeing Taylor Blau
2023-06-07 10:41   ` [PATCH v3 04/16] ref-filter: add `ref_filter_clear()` Taylor Blau
2023-06-07 10:41   ` [PATCH v3 05/16] ref-filter.c: parameterize match functions over patterns Taylor Blau
2023-06-13 22:37     ` Junio C Hamano
2023-06-07 10:41   ` [PATCH v3 06/16] builtin/for-each-ref.c: add `--exclude` option Taylor Blau
2023-06-07 10:41   ` [PATCH v3 07/16] refs: plumb `exclude_patterns` argument throughout Taylor Blau
2023-06-13 23:42     ` Junio C Hamano
2023-06-20 11:52       ` Taylor Blau
2023-06-07 10:41   ` [PATCH v3 08/16] refs/packed-backend.c: refactor `find_reference_location()` Taylor Blau
2023-06-07 10:41   ` [PATCH v3 09/16] refs/packed-backend.c: implement jump lists to avoid excluded pattern(s) Taylor Blau
2023-06-14  0:27     ` Junio C Hamano
2023-06-20 12:05       ` Taylor Blau
2023-06-20 18:49         ` Junio C Hamano
2023-06-07 10:41   ` [PATCH v3 10/16] refs/packed-backend.c: add trace2 counters for jump list Taylor Blau
2023-06-14  0:32     ` Junio C Hamano
2023-06-20 12:08       ` Taylor Blau
2023-06-07 10:41   ` [PATCH v3 11/16] revision.h: store hidden refs in a `strvec` Taylor Blau
2023-06-07 10:41   ` [PATCH v3 12/16] refs/packed-backend.c: ignore complicated hidden refs rules Taylor Blau
2023-06-14  0:40     ` Junio C Hamano
2023-06-07 10:41   ` [PATCH v3 13/16] refs.h: let `for_each_namespaced_ref()` take excluded patterns Taylor Blau
2023-06-07 10:42   ` [PATCH v3 14/16] builtin/receive-pack.c: avoid enumerating hidden references Taylor Blau
2023-06-07 10:42   ` [PATCH v3 15/16] upload-pack.c: avoid enumerating hidden refs where possible Taylor Blau
2023-06-07 10:42   ` [PATCH v3 16/16] ls-refs.c: " Taylor Blau
2023-06-12 21:05   ` [PATCH v3 00/16] refs: implement jump lists for packed backend Junio C Hamano
2023-06-20 14:20 ` [PATCH v4 " Taylor Blau
2023-06-20 14:21   ` [PATCH v4 01/16] refs.c: rename `ref_filter` Taylor Blau
2023-07-03  5:13     ` Jeff King
2023-06-20 14:21   ` [PATCH v4 02/16] ref-filter.h: provide `REF_FILTER_INIT` Taylor Blau
2023-07-03  5:15     ` Jeff King
2023-07-03 17:07       ` Taylor Blau
2023-06-20 14:21   ` [PATCH v4 03/16] ref-filter: clear reachable list pointers after freeing Taylor Blau
2023-07-03  5:16     ` Jeff King
2023-06-20 14:21   ` [PATCH v4 04/16] ref-filter: add `ref_filter_clear()` Taylor Blau
2023-07-03  5:19     ` Jeff King
2023-07-03 17:13       ` Taylor Blau
2023-07-03 17:32         ` Jeff King
2023-06-20 14:21   ` [PATCH v4 05/16] ref-filter.c: parameterize match functions over patterns Taylor Blau
2023-07-03  5:27     ` Jeff King
2023-07-03 17:18       ` Taylor Blau
2023-07-03 17:22         ` Taylor Blau
2023-07-03 17:33           ` Jeff King
2023-06-20 14:21   ` [PATCH v4 06/16] builtin/for-each-ref.c: add `--exclude` option Taylor Blau
2023-06-20 14:21   ` [PATCH v4 07/16] refs: plumb `exclude_patterns` argument throughout Taylor Blau
2023-06-20 14:21   ` [PATCH v4 08/16] refs/packed-backend.c: refactor `find_reference_location()` Taylor Blau
2023-06-20 14:21   ` [PATCH v4 09/16] refs/packed-backend.c: implement jump lists to avoid excluded pattern(s) Taylor Blau
2023-07-03  5:56     ` Jeff King
2023-07-03 17:38       ` Taylor Blau
2023-06-20 14:21   ` [PATCH v4 10/16] refs/packed-backend.c: add trace2 counters for jump list Taylor Blau
2023-06-20 14:21   ` [PATCH v4 11/16] revision.h: store hidden refs in a `strvec` Taylor Blau
2023-07-03  5:59     ` Jeff King
2023-06-20 14:22   ` [PATCH v4 12/16] refs/packed-backend.c: ignore complicated hidden refs rules Taylor Blau
2023-07-03  6:18     ` Jeff King
2023-07-04 18:22       ` Taylor Blau
2023-06-20 14:22   ` [PATCH v4 13/16] refs.h: let `for_each_namespaced_ref()` take excluded patterns Taylor Blau
2023-06-20 14:22   ` [PATCH v4 14/16] builtin/receive-pack.c: avoid enumerating hidden references Taylor Blau
2023-06-20 14:22   ` [PATCH v4 15/16] upload-pack.c: avoid enumerating hidden refs where possible Taylor Blau
2023-07-03  6:26     ` Jeff King
2023-07-04 18:43       ` Taylor Blau
2023-06-20 14:22   ` [PATCH v4 16/16] ls-refs.c: " Taylor Blau
2023-07-03  6:27     ` Jeff King
2023-07-03  6:29   ` [PATCH v4 00/16] refs: implement jump lists for packed backend Jeff King
2023-07-10 21:12 ` [PATCH v5 " Taylor Blau
2023-07-10 21:12   ` [PATCH v5 01/16] refs.c: rename `ref_filter` Taylor Blau
2023-07-10 21:12   ` [PATCH v5 02/16] ref-filter.h: provide `REF_FILTER_INIT` Taylor Blau
2023-07-10 21:12   ` [PATCH v5 03/16] ref-filter: clear reachable list pointers after freeing Taylor Blau
2023-07-10 21:12   ` [PATCH v5 04/16] ref-filter: add `ref_filter_clear()` Taylor Blau
2023-07-10 21:12   ` [PATCH v5 05/16] ref-filter.c: parameterize match functions over patterns Taylor Blau
2023-07-10 21:12   ` [PATCH v5 06/16] builtin/for-each-ref.c: add `--exclude` option Taylor Blau
2023-07-10 21:12   ` [PATCH v5 07/16] refs: plumb `exclude_patterns` argument throughout Taylor Blau
2023-07-10 21:12   ` [PATCH v5 08/16] refs/packed-backend.c: refactor `find_reference_location()` Taylor Blau
2023-07-10 21:12   ` [PATCH v5 09/16] refs/packed-backend.c: implement jump lists to avoid excluded pattern(s) Taylor Blau
2023-07-10 21:12   ` [PATCH v5 10/16] refs/packed-backend.c: add trace2 counters for jump list Taylor Blau
2023-07-10 21:12   ` [PATCH v5 11/16] revision.h: store hidden refs in a `strvec` Taylor Blau
2023-07-10 21:12   ` [PATCH v5 12/16] refs.h: let `for_each_namespaced_ref()` take excluded patterns Taylor Blau
2023-07-10 21:12   ` [PATCH v5 13/16] refs.h: implement `hidden_refs_to_excludes()` Taylor Blau
2023-07-10 21:12   ` [PATCH v5 14/16] builtin/receive-pack.c: avoid enumerating hidden references Taylor Blau
2023-07-10 21:12   ` [PATCH v5 15/16] upload-pack.c: avoid enumerating hidden refs where possible Taylor Blau
2023-07-10 21:12   ` [PATCH v5 16/16] ls-refs.c: " Taylor Blau
2023-07-10 22:35   ` [PATCH v5 00/16] refs: implement jump lists for packed backend Junio C Hamano
2023-07-11  9:37     ` Patrick Steinhardt
2023-07-11 15:56       ` Junio C Hamano
2023-07-11 17:19         ` Taylor Blau

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